<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
    <style>
        .header{
            height: 70px;
            background-color:#f8f8f8;
        }
        .header-left{
            width: 50%;
        }
        .header-right{
            width: 50%;
        }
    </style>
</head>
<body>
    <div class="header">
        <div class="header-left">

        </div>
        <div class="header-right"></div>
    </div>
    <div class="body"></div>
    <div class="footer"></div>
<script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.min.js"></script>
<script src="https://cdn.bootcss.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
</body>
</html>